Declining water quality problem for N.D. livestock

August 22, 2008

As the drought conditions persist in western North Dakota, producers should pay attention to water quality and availability, says Charlie Stoltenow, North Dakota State University Extension Service veterinarian. The toxicology section of NDSU's Veterinary Diagnostic Laboratory has reported a number of water samples from western and north-central North Dakota with sulfate levels and total dissolved solids (TDS, a measure of salinity) too high for livestock to consume safely. The lab has found sulfate levels in excess of 4,000 to 5,000 parts per million (ppm) and TDS levels in excess of 8,000 to 10,000 ppm. These samples have been taken primarily from sloughs, ponds, dugouts and stock dams. Sulfate levels should be less than 1,000 to 1,500 ppm and TDS levels should be less than 5,000 ppm for most classes of grazing livestock, according to Michelle Mostrom, NDSU veterinary toxicologist. Higher TDS levels may not have negative effects on animal health, provided specific ions such as sulfate are not in the toxic range. However, in North Dakota, well water high in TDS often is high in sulfates. Thus, sulfate often is a health concern because the acceptable sulfate level will be exceeded before TDS levels are high enough to be a problem. High levels of sulfate in the water also reduce copper availability in the diet, while sulfate levels as low as 1,000 ppm may result in scours. Greg Lardy, NDSU Extension beef specialist, advises producers to dilute high-sulfate water with low-sulfate water or find another water source. Producers also need to take into account sulfur from dietary sources. Total sulfur levels (water and dietary sources) should not exceed 0.5 percent for forage-fed cattle. In most situations, this results in water sulfate recommendations of less than 1,000 to 1,500 ppm. Corn byproducts, such as distillers grains and corn gluten feed, contain relatively high levels of sulfur. Therefore, producers with poor quality water should evaluate supplementation programs carefully to determine overall sulfur intake to reduce the risk of sulfur toxicity associated with poor quality water. Lardy says high levels of sulfates from either water or dietary sources may contribute to an increased incidence of polioencephelomalacia (PEM), a brain disorder found in cattle. If producers suspect copper deficiency problems, they should have water sources analyzed to determine if high sulfate levels are contributing to the problem. "If you have any doubts about water quality, get it tested," Stoltenow says. "Cattle need water and lots of it." At temperatures in excess of 95 F, cattle need at least 1 gallon of water for every pound of feed on a dry-matter basis. For a 1,200 pound cow, that is about 20 gallons per day. "Without significant rainfall to recharge ponds, sloughs and dugouts, water quality is likely to continue to decline as water evaporates from existing sources," Lardy says. "Taking steps now to evaluate water sources and prevent problems will pay dividends." For more information on water quality, check out NDSU Extension publication AS- 954, "Livestock and Water," at http://www.ag.ndsu.edu/pubs/h2oqual/watanim/as954.html.